That would be a good idea. But see there is this one problem. You got to tell us what you want out of the engine? HP wise, etc... For instance, will you ever put a blower on it? If so, then DO NOT run 10.5:1 comp! If you stay N/A then thats great! If your future goals will never reach about 500 hp then you can retain the stock block. You can go the cheap way and do a 306 for about 1100 bucks. Thats keeping the stock rods and polishing the crank. You gotta know what your final goal with the engine is before you start messing with it. Its never a good ideal to just buy parts and slap them together without a plan
As one guy mention you can do a H/C/I kit(TFS, FRPP, Holley etc..) A 306 with AFR 165's, GT-40 intake, and camshaft would be a great combo. Also, cheap btw! Now that combo on a 331 would suck. So if you want a 331 you got to make up your mind first before you buy parts, always start from the bottom up!